It is desirable following injection of a medicament into a patient to wait a short time before withdrawing the needle unit from the body of the patient. This is because the injected medicament takes a few seconds to disperse locally from the injection site within the body of the patient. If the needle unit is withdrawn too soon after the medicament has been injected, there is a risk that at least some of the injected medicament may escape through the needle wound and not be dispersed into the patient as is desired.
Unfortunately, this problem is particularly acute where a patient uses a medicament injection apparatus to self-administer a medicament. A user may become impatient and withdraw the needle before the medicament has dispersed.
Where this waiting period is indicated to a user, for example by way of display or audible sound in known medicament delivery apparatus, the waiting period is a set time independent of whether the dose size of medicament to be injected is large or small. The user may feel that for a small dose it is not as important to leave the needle unit within the body of the patient for the full waiting period. Unfortunately, it is often the case that the user no longer allows the waiting period to elapse in the belief that the waiting period is not critical.
It is an advantage that the present invention seeks to alleviate this problem.